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03-30-2011, 12:56 AM
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1st Gear
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Join Date: Mar 2011
Posts: 2
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A4 1.8T cold start problem - low rpm
When my A4 B5 1.8T sits for 10 hours or longer, it needs quite a few cranks (10 seconds or so) until it starts. Even then, it starts slowly and rough.
When it was working fine, rpms would go higher in the first minute after a cold start, bu it no longer does that. Almost like a missing "choke" - or whatever the equivalent is for these engines.
Do you know what controls the rpm increase for a cold engine? What could cause them to stay low like it would be for a warm engine?
I already cleaned the MAF, replaced fuel filter + spark plugs. Temp display is fine otherwise, but I'll try replacing the sensor next.
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03-30-2011, 10:09 AM
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1st Gear
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Join Date: Mar 2011
Location: Upstate NY
Posts: 50
Level up: 14%, 86 Points needed |
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On the first start of the day mine idles low as well. Any other cold start (but not the first start in a long period of time such as an overnight) it will idle high, as it should, for about a minute.
No clue what this is all about either...
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04-03-2011, 01:08 AM
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1st Gear
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Join Date: Mar 2011
Posts: 2
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Swapping out the coolant temp sensor fixed my cold start problem.
I didn't think it would since the temp gauge showed correct values, but maybe it's driven by another sensor.
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04-03-2011, 02:58 PM
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1st Gear
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Join Date: Jan 2011
Posts: 192
Level up: 52%, 48 Points needed |
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Does the idle surge?
What is a "high" idle for you?
Cold start mine will be about 850 all day long. Warm start again,850. My coolant temp gauge is shot and no starting problems.
I would definitely check the sensor governing the intake air temp and maybe check 02's? Could be something simple, could be...lol
Another thing to check are vacuum lines!!!
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04-03-2011, 10:42 PM
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1st Gear
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Join Date: Jan 2011
Location: Lewistown, PA
Posts: 243
Level up: 30%, 106 Points needed |
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shot in the dark but
Starter solenoid? Starter Motor? Loose wiring in the starting circuit?
Like wise, mine starts in 2-3 seconds and idles at 850 hot/cold
__________________
Project "Kleen" Cancelled, new project "survive to 300k Miles" 
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04-04-2011, 12:48 AM
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1st Gear
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Join Date: Jun 2006
Location: NyC - Manhattan
Posts: 228
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Replace the hall sender / crank position sensor. Usually when these sensors are cold, they have less electrical resistance, while warm they may function well but not when cold.
__________________
www.iWantToGoFast.net - DM Technik Long Island, NY.
-98.5 A4 1.8t - RIP
-01 A4 1.8t hta3076 - Engine RIP -> 2.7t Swap SOLD!
-95 UrS6 2.2t - Stock.. For now =).
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04-04-2011, 01:23 AM
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1st Gear
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Join Date: Apr 2010
Posts: 203
Level up: 53%, 71 Points needed |
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See if your suction pump is disconnected. Happened to me and caused starting problems.
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04-04-2011, 01:32 AM
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1st Gear
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Join Date: Apr 2011
Posts: 5
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The rpm's are fine. It's just that if the engine is cold, you can floor it and get only a turtle crawl. Once warm, problem only occurs during wide turns.
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04-05-2011, 09:10 PM
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1st Gear
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Join Date: Jan 2011
Posts: 192
Level up: 52%, 48 Points needed |
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During wide turns??????????
Fuel? does anyone else think it could possibly be a fuel pump?
How cold is it outside?
The turns thing is very confusing
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04-05-2011, 09:10 PM
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Tags
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18, 18t, a4, audi, b5, cold, coolant, location, power, problem, revs, rpm, sensor, shifts, start  |
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